KR20030087874A - Multi-level Security Method for Data on Computing Device based on security levels assigned to data or applications - Google Patents

Abstract

PURPOSE: A method for the leveled data security of a computing device is provided to secure security and convenience simultaneously by dividing the data into each level according to the security necessity and applying a different security algorithm to each level. CONSTITUTION: After certifying and permitting the access to the device, a security level of the data is confirmed if the data access is requested from an application program of a security management program module(S215). The data access is certified by carrying out the security algorithm previously set to the confirmed security level(S217,S218,S219). In case of the access certification according to the result carrying out the security algorithm, the data access is permitted(S221).

Description

Multi-level Security Method for Data on Computing Device based on security levels assigned to data or applications}

The present invention relates to a class-specific security method for data of a computing device, and more particularly, to a method of hierarchizing data stored in a computing device according to a security level and applying a different security algorithm to each layer.

Due to the development of computer or wireless communication technology, important tasks of corporations or individuals are mostly performed by computing devices, and thus, many important data are stored and managed in computing devices.

In particular, since the conventional main confidential information was mainly stored in a fixed personal computer (PC), the leakage of the information stored in the PC was also guaranteed as long as the space where the PC is located is maintained. Accordingly, the use of mobile computing devices such as mobile communication terminals, PDAs (Personal Digital Assistants), and laptops is increasing the number of communication and other tasks without the restriction of places, and thus the need for security of data stored in the mobile computing devices is increasing. It is increasing.

In particular, it is easy to lose due to the characteristics of the mobile computing device, and if it is lost, important data may be leaked to others and may be fatally damaged, thereby increasing the need for security.

In order to overcome this disadvantage, the following security methods are used.

In the first form, there is a method of controlling access to the device by using a password or lock function.

Here, if a user sets a lock function in a state in which the password set by the user is stored in the memory of the device, a password must be input when an illegally acquired person attempts to use the device or unlock the device. We used a method to check whether the password matches the stored password. In the case of authentication through password input, all data in the mobile computing device (access, modification, deletion, etc.) was possible.

Even when using this method, there is a risk that stored data may leak when a person who illegally acquires a device finds and unlocks a password of the device.

In addition, when the password is stored in the storage of the device, a person who illegally acquires the device may find out the password by disassembling or cracking the device.

To this end, recently developed PDAs use a proper hash function to extract a hash value for the password initially set by the user and store it in a suitable storage, which is then used for user authentication or device access control. I use it. A "hash function" is a one-way function that converts input values of various lengths into fixed short length output values, that is, hash codes. The general content of these hash functions is described in more detail below.

Turn on the PDA, allow the user to enter a password before running an operating system (OS) such as Palm or WinCE, and verify that the hash value for the entered password matches the stored hash value. Only if you do this process to allow the operation of the PDA. In other words, access to the device is performed by the user entering a password, and the input routine obtaining the hash value on-the-fly and comparing the hash value of the user stored in the device.

To this end, a hash value for a password selected by a legitimate user in advance when the device is set should be stored.

In this method, since the password is not simply stored as a combination of numbers and letters, it is stored as a hash value that is an arbitrary digital value of 128 or 160 bits. Even when disassembling or cracking the memory, only the hash value of the password in the memory is known and the actual password is not known, thereby preventing access to the computing device through the password input for enhanced security.

As a second security method, individual security methods for data can be used.

In this method, important information in the device is always encrypted and stored, and only when the application program displays the information, the encrypted information is decoded and displayed on the fly, and the newly edited information is stored again, or When the power is turned off, encrypt and save again. Such encryption / decryption is performed in a key manner, and an appropriate encryption / decryption algorithm may be used.

To this end, no temporary file or image of unencrypted information should be present other than the encrypted information in the device. In particular, when a virtual memory is used, a password file or a key value in the memory may be caught in a swap page by an operating system, and a swap file such as an external hard disk or another persistent storage device may be used. It should be prevented from being saved in the swap file.

The third form is a security method that combines the first and second methods, extracts the hash value for the password, encrypts the encryption / decryption key necessary for encrypting the data using the hash value as the first key, Stores encrypted encryption / decryption keys in a specific memory of the device.

All data of the device is encrypted and stored by an encryption / decryption key, decrypted and displayed when viewed by an application, and encrypted by the encryption / decryption key when stored or powered off again.

The encryption / decryption key needed for data encryption / decryption is read from memory only when necessary, and then decrypted using the hash value of the password to be temporarily used in memory, which does not cause swapping or other image files. It is destroyed without.

However, even if the second or third data security method is used, the following disadvantages exist.

First, if the password hash value or the encryption / decryption key used for encrypting / decrypting data is stored in the memory of the device, security becomes impossible. In other words, when an illegally acquired device analyzes or cracks a device's memory or the like, the hash value of the password or the encryption / decryption key can be found, thereby incomplete security. In other words, since information (hash values, encryption / decryption keys) that allow access to data is stored in the device, complete security is not possible.

Also, because all data is protected in the same way, no consideration is given to the security of the data. For example, it is necessary to apply simple and fast security algorithms for data with relatively low security needs and strict security algorithms for data with high security needs. When applying a security algorithm, it may take time and make the user feel uncomfortable. Therefore, it is necessary to apply a different security method for each data in order to promote both security and ease of use.

Meanwhile, recently, as a mobile computing device capable of wireless communication is widely used, methods and systems for managing data of the mobile computing device in a central server have been introduced. In this regard, the Korean application filed by the present applicant discloses a data integrated management and sharing method using a system consisting of one or more data communication devices capable of communicating with the web server through a web server and the Internet. Doing.

The present invention has been made in view of the above, and by introducing the above-mentioned data integrated management method and the security method for each layer or class for the data in the computing device, to secure both security and ease of use.

It is an object of the present invention to provide a class or layer security method for data of a computing device.

Another object of the present invention is to classify data of a mobile computing device into layers according to security needs, and to apply a different security algorithm to each layer, thereby providing a data security method capable of simultaneously securing security and convenience of use. It is.

1 schematically illustrates a configuration of a computing device in which a layered data security method according to the present invention is performed.

2 is a diagram schematically showing the overall flow of the data security method for each layer according to the present invention.

3 is a diagram for describing a security algorithm according to the first method of the present invention, that is, a security algorithm for a data level (level 3) having the lowest security need.

4 is a diagram for describing a security algorithm according to the second method of the present invention, that is, a security algorithm for a data security level (level 2) having a moderate security need.

FIG. 5 is a diagram for describing a security algorithm according to a third method of the present invention, that is, a security algorithm for level 1 data having the highest security need.

6 is a diagram for explaining an example of another security algorithm using life time.

In order to achieve the above object, the layered data security method of the computing device according to the present invention has the following features.

A data security method for each layer of a computing device having a security management program module,

After user authentication and / or device access to the device, the security management program module checks the security level of the requested data when there is a request for access to specific data from the application program of the device

Performing a predetermined security algorithm according to the checked security level to perform an access authentication on the corresponding data;

As a result of performing the security algorithm, the method may include a data processing step of allowing access to the corresponding data only when the access is authenticated.

The verification of the security level may be performed by referring to meta data stored in a computer device or an external server. This metadata means a file that contains basic information about the data, such as data title, author, creation date and time, security level, and the like. Meta data may exist as part of the data by using a tag such as XML (eXtensible Markup Language), or may exist as another metafile. Metadata can only be edited by authorized personnel or devices.

In the security algorithm performing step and data processing step, the following three methods may be applied alone or in combination.

First, the first security method is a first step of extracting or calculating an encryption / decryption key stored in the device without individual authentication for each data, and decrypting the corresponding data by using the extracted or calculated encryption / decryption key to the application program. It may comprise a second step of delivering.

The second security method includes a first step of receiving device or user authentication from an external server or device interworking with a computing device, a second step of receiving an encryption / decryption key for decrypting data from the external server or device, and receiving And a third step of decrypting the corresponding data using the encryption / decryption key and transferring the data to the application program.

The third security method includes a first step of authenticating a user or a device from an external server or device interworking with a computing device, a second step of receiving an encryption / decryption key for decrypting data from the external server or device, and A third step of decrypting the corresponding data using an encryption / decryption key and transferring the data to the application program; and monitoring whether the lifetime given to the data requested for access has ended, and if the expiration of the lifetime is imminent. A fourth step of causing the user to enter a life time extension password, and a fifth step of transmitting a life time extension request to the external server when the life time extension password (or a hash value of the password) is identical; If the life time extension is approved by the server, the life time of the data is extended and renewed. This is followed by a sixth step that allows access to the data.

Of course, the third security method may not be performed only when there is a request for access to specific data. That is, the security management program monitors the life time of the data stored in the device, and if the expiration of the life time is imminent, prompting the user to enter a life time extension password, When the passwords match, the life time extension request is transmitted to the external server, and the life time extension request may be further updated only when the life time extension request is authenticated.

That is, for vital data given life time, whether life time expires is always monitored regardless of whether access to data is being performed, and extension of expired data is performed.

In addition, if necessary, the user authentication is performed every predetermined period after the data processing step, and the data processing step is continued only when the user re-authentication is performed. If the user re-authentication fails, the data processing is terminated. The method may further include a user reauthentication step of encrypting and storing the processed data.

In addition, after the data processing step, when the work on the data is finished or the power of the device is turned off, it is preferable to encrypt and store the data at that time.

Here, "access" or "processing" for data refers to other computing devices, in addition to opening, editing, writing, deleting, and copying the data. It should be understood as a broad concept involving transfer.

It is also desirable to compress all data prior to being encrypted (using pkzip, etc.), and to use a different encryption / decryption key than before if the device is turned off once and then turned on again. That is, the first encryption / decryption key is used to access and decrypt data for the first time after the device is turned on again, but a new encryption / decryption key is generated and used when storing the data again. At this time, the new encryption / decryption key combines random information generated by a pseudo random number generator, specific information such as today's time, and existing seed information (for example, XOR, etc.). And then hash it again or encrypt it. In this case, the first seed information may be a random number extracted based on a user's input behavior, that is, a key stroke or a mouse movement.

By doing so, the hierarchical or level security of data stored in the computing device is enabled, thereby improving the efficiency and reliability of data security.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

1 schematically illustrates a configuration of a computing device in which a layered data security method according to the present invention is performed.

The computing device to which the present invention is applied includes a central computing unit (CPU) 110, an input device 120 such as a keyboard or a touch screen, an output device 130 such as a monitor or a liquid crystal screen, and a storage space for storing data. In addition to the memory 140, a security management program module 150 for implementing a graded data security algorithm according to the present invention is provided. In addition, a plurality of application programs 160 that require access to data in a computing device are provided.

In addition, a data transmission / reception module 170 such as a wireless communication chip may be further provided for interworking with an external server.

The security management program module 150 may be implemented in either hardware or software. However, the security management program module 150 may be implemented in software so as to be commonly applied to all devices.

Computing device 100 in which the present invention can be used includes all the devices that need security because it stores important data, for example, a mobile phone, a PDA, a handheld PC, a notebook, a personal computer (PC). ), Etc.

Accordingly, the input device 120 may be any means such as a keyboard, a voice input device such as a microphone, a touch screen, a touch pen, and the like, and the output device may be a CRT, a TFT, or an LCD monitor.

In addition, an appropriate operating system should be built according to the type of the device. Such an operating system (OS) may be, for example, Windows, Linux, DOS in the case of a PC or a notebook, and Win CE, Linux OS, Cellvic OS, Palm OS, or the like in the case of a PDA. In addition, the application program 160 requiring access to data may be, for example, a word processor, an address book program, a web browser (such as WAP or ME), or the like.

All data stored in the computing device 100 used in the present invention is preferably in an encrypted state except for a period of input / output in the input / output device. That is, when a request is made to view some data on an output device (screen, etc.), the central processing unit retrieves the corresponding data from the memory (RAM, FlashROM, hard disk, etc.) and displays the data on the output device at the request. .

At this time, the decrypted data exists only in the screen (output device) and the temporary memory for display, and when the display is finished, the decrypted data in the temporary memory is immediately deleted. Here, "Delete" is not a simple method of deleting a list from a File Allocation Table (FAT), but overwriting the original data one or more times with a "010101…" sequence or a random number. This means removing them from the file list table.

In addition, even when the decrypted data is edited using the input device 120 and the edited data is stored again, when the user gives a storage command, the data is immediately encrypted and stored in the memory.

In the present specification, it is preferable to use an encryption algorithm based on a symmetric key when encrypting or decrypting data. Symmetric algorithms based on symmetric keys include DES, IDEA, AES, SEED, etc. In the symmetric key-based encryption algorithm, the same key is used for encryption and decryption.

2 is a diagram schematically showing the overall flow of the data security method for each layer according to the present invention.

First, when the user authentication (S211, S212) and the access permission (S213) to the device through the password input or the like, the user selects and executes the required application program (S214).

When the user requests access to specific data using an application program (S215), the security management program module interrupts the data access request and checks the security level of the corresponding data (S216). The security level can be checked by referring to the metadata of the data.

In this embodiment, the data is divided into three levels of security according to importance, but the present invention is not limited thereto and may be divided into more or less levels. It is assumed that level 1 is the most important data and the highest security level, and level 3 is the lowest security level.

After checking the security level of the data requested for access, the security management program module executes an appropriate security algorithm according to the security level of the corresponding data (S217 to S219), and permits access to the data only in case of authentication. Respective security and data processing algorithms for levels 1 to 3 are described in more detail below with reference to FIGS.

In addition, in order to improve security, user authentication may be periodically performed when necessary (S220). For example, user authentication is performed by inputting a password or the like at predetermined time intervals, and data processing is allowed only when authentication is successful. If periodic user authentication fails, forcibly delete all temporary files and variables, send a processing termination signal to the application program that was executing the data, encrypt and save the processed data, and lock the device. The power can be turned off (S221. S222).

By periodically re-authenticating the user (password entry), it is possible to prevent illegal use by unauthorized persons when the device is turned on for a long time without a user or when it is lost. At this time, the period may be determined by the attribute of the data. In other words, the more sensitive data is, the more often user re-authentication can be performed.

It is assumed that the grantor of the security level for the data is the creator of the original data.

In addition, although the above assumes that a security level is assigned to the data, a similar purpose can be achieved by assigning a security level to each application program.

3 is a diagram for describing a security algorithm according to the first method of the present invention, that is, a security algorithm for a data level (level 3) having the lowest security need.

If the security level of the requested data is level 3, routine data processing is performed. First, an encryption / decryption key (Keydata) stored in the memory of the device is extracted or calculated (S311), and the requested data is decrypted using the encryption / decryption key (S312). The decrypted data is once output (S313) and then processed according to the processing method requested by the application. That is, when the requested processing method is "Read" or "Open", the decrypted data is simply output (S315), and the requested processing method is "Write" or "Edit (Edit). ), The data at that time is encrypted and stored (S316).

In addition, when the requested processing method is "Delete", "Copy", "Transfer", the corresponding process is performed (S317).

However, in order to increase security, important approaches such as "delete", "copy", and "transfer" may be performed after user authentication is separately performed (S318 and S319).

In the first security algorithm, when the central processing unit (CPU) or an application program requests reading of data, etc., it displays the output or uses the data as intermediate data within the program. . Therefore, when the decoded data is output or used as intermediate data in the program, not all of them are permanently stored.

In addition, in the first security algorithm, an encryption / decryption key (Keydata) used for encryption / decryption of data is preferably encrypted and stored in the memory of the device. Thus, an embodiment of encrypting an encryption / decryption key is as follows.

First, a random random number is generated based on a user's arbitrary input behavior, for example, a key stroke interval, a touch screen input behavior, and the like, and a cryptographic / decryption key for data is generated. Use as. If the encryption / decryption key is stored in the memory as it is, it may be leaked. Therefore, the encryption / decryption is encrypted by encrypting the encryption / decryption key with the hash value H (password) of the password used for user authentication. Generates a key Eth (Keydata) and stores it in a specific space in memory. This is summarized as follows.

-Hash value for password: H (password)

-Data encryption / decryption key: Keydata

-Encrypted data encryption / decryption key: Eth (Keydata)

The size of H (password), which is a key used to encrypt Keydata, which is a data encryption / decryption key, needs to be adjusted according to the encryption algorithm. For example, when encrypting data encryption / decryption keydata with AES encryption algorithm, encryption key requires 128 bits, but if SHA-1 is used to hash password, 160-bit hash value is generated. Therefore, in this case, only the first 128 bits of the hash value 160 bits may be used as long as the length of the key needed to encrypt the data encryption / decryption key among the hash values.

Thus, when the encryption / decryption key is encrypted and stored, once the encrypted encryption / decryption key (Eth (Keydata)) is retrieved to perform the first security algorithm, Keydata = E-1kh (Eth (Keydata)). It should be used after calculating the encryption / decryption key data using the following formula.

In addition, when the power is turned off during the data processing by the first algorithm or the processing for the data is normally completed, it is preferable to automatically encrypt and store the current data (S320).

4 is a diagram for describing a security algorithm according to the second method of the present invention, that is, a security algorithm for a data security level (level 2) having a moderate security need.

The second security algorithm and data processing scheme for level 2 data assumes that no data encryption / decryption key (Keydata) is stored in the computing device. That is, data encryption / decryption key must be transmitted from an external device, and data in the device is absolutely secure unless a valid encryption / decryption key is transmitted from the outside.

In detail, when the security level of the data requested for access is level 2, the security management program module initiates a level 2 data processing session (S411), and then transmits an encryption / decryption key request to an external server. (S412). When the encryption / decryption key transmission request is requested, the authentication information is transmitted together so that the external server can authenticate the device or the user. Of course, if necessary, the identification information of the corresponding data may be transmitted together with the authentication information (S412).

The communication line or channel through which the server and device communicate is assumed to be secured as a secure tunnel, such as a secure VPN or a special secure channel.

The following manner may be used for the device to authenticate itself from the server. First, if the asymmetric encryption method is used between the device and the external server, the electronic signature can be used. If the symmetric encryption method is used between the device and the external server, the secret information shared by the device and the external server can be timed. By adding a time stamp, the timestamp is sent together with the hashed value and plain text, and an external server can use it to authenticate the device.

When the external server legitimately authenticates the user or the device in the above-described manner, the external server transmits the encryption / decryption key stored in the device to the device (S414).

Of course, if the device is not authenticated, it may not simply transmit an encryption / decryption key, but for the sake of security, a so-called "suicide signal" may be sent to the device to delete all programs and / or data in the device. It may also be (S423).

After the encryption / decryption key is transmitted to the device due to the successful authentication, data processing is performed in a manner similar to the first security algorithm described above. That is, the data is decrypted and output once using the encryption / decryption key (Keydata) received from the external server (S415). The decrypted data is processed according to the requested processing scheme. That is, if the requested processing method is "Read" or "Open", the decrypted data is simply output (S417), and the requested processing method is "Write" or "Edit (Edit). ), The data at that time is encrypted and stored (S418).

In addition, if the requested processing method is "Delete", "Copy", "Transfer", the corresponding process is performed. However, in order to increase security, important approaches such as "delete", "copy", and "transfer" may be performed after receiving user authentication separately (S419 to S421).

In addition, although not shown, the second security algorithm must essentially block the level 2 data encryption / decryption key from being stored in the device by discarding the encryption / decryption key at the end of the level 2 data processing session.

In the above, the "external server" is used as an example for providing an encryption / decryption key in the second security algorithm, but is not limited thereto. A smart card, an IC card, a subscriber identification module (SIM) card, or the like may be used. It may be provided with an encryption / decryption key from another external device.

FIG. 5 is a diagram for describing a security algorithm according to a third method of the present invention, that is, a security algorithm for level 1 data having the highest security need.

The third security algorithm is a security method for the highest security level 1 data, and assumes that no encryption / decryption key (Keydata) is stored in the device similarly to the second security algorithm. Each Level 1 data is assigned a Lifetime and Lifetime Extension password.

The third security algorithm and data processing method will be described in detail as follows.

First, as in the second security algorithm, the security management program module confirms that the security level of the data requested for access is level 1, initiates a level 1 data processing session, and then sends an encryption / decryption key transmission request to an external server. do. When the encryption / decryption key transmission request is requested, the authentication information is transmitted together so that the external server can authenticate the device or the user. At this time, the authentication information, like the second security algorithm, uses a digital signature in an asymmetric encryption scheme, or adds a timestamp to the secret information in a symmetric encryption scheme and forms a plain text format. A timestamp of is available. Of course, the device and the server designate in advance what information is confidential.

When the external server legitimately authenticates the user or the device in the above-described manner, the external server transmits the stored encryption / decryption key to the device.

Of course, if the device is not authenticated, it may not simply transmit an encryption / decryption key, but for the sake of security, a so-called "suicide signal" may be sent to the device to delete all programs and / or data in the device. It may be.

After the encryption / decryption key is transmitted to the device by the successful authentication, data processing is performed. That is, the requested data is decrypted using the encryption / decryption key (Keydata) received from the external server. The decrypted data is processed according to the requested processing scheme. That is, when the requested processing method is "Read" or "Open", the decrypted data is output. When the requested processing method is "Write" or "Edit." The data at that time is encrypted and stored.

In addition, if the requested processing method is "Delete", "Copy", "Transfer", the corresponding process is performed. However, in order to increase security, important approaches such as "delete", "copy", and "transfer" may be performed after a separate user authentication.

Since the above procedure is the same as the second security algorithm, illustration is omitted.

Next, unlike the second security algorithm that continues to process the data once authenticated, a security daemon in the security management program module continuously monitors the lifetime of the data. If the expiration of the corresponding data life time is imminent (S511), the user is warned to apply for a life time extension, and enters a password for life time extension (S512). This security daemon is a system software that cannot be deleted / stopped by the user.

To extend the life time, according to the password input request for extending the life time of the security daemon, the user enters the life time extension password (S513), the security daemon checks whether the password is correct (S514), life time to the external server The extension request is transmitted (S515). Of course, if the input password for extending the life time does not match the stored value, the processing for the corresponding data is stopped, the data is encrypted and stored, or the data is deleted (S516, S523).

When the life time extension request is made to the server, the authentication information and data identification information for authentication of the device are transmitted together (S515). The authentication information for extending the life time may use the same or similar method as the authentication information for receiving the encryption / decryption key. In other words, a digital signature, a hash value of secret information + timestamp, and a plain text timestamp value can be used.

At this time, the life time extension password may be the same as or different from the user or device authentication password.

After the external server determines whether the life time extension is approved (S517), if the extension is possible, the new life time information is transmitted to the device (S518), and the device updates the life time of the corresponding data and continues to use it. (S519).

If it is impossible to extend the life time, the external server transmits an additional response request to the device (S520). "Additional response request" is a command for an action that a device should take if it is impossible to extend its lifespan. For example, simply encrypt the data and store it, ask the user additional questions, or turn off the device after deleting the data. It may be a command (S521).

Of course, if the processing for level 1 has ended normally (S522), or if the authentication of the life extension password and the approval of the life extension from the server have failed, the device encrypts and stores the data being processed (S523). ), Deletes the encryption / decryption key of the corresponding Level 1 data.

That is, in the third security algorithm using life time, the security is improved by performing the first authentication for obtaining the encryption / decryption key from the server and the second authentication for obtaining the approval for extending the life time.

As described above, the security algorithm using life time may not necessarily be applied only while the corresponding data is being processed.

6 is a diagram for explaining an example of another security algorithm using life time.

With permission to access the device (S611, S612), the security daemon monitors the life time for all data of the level 1 (including data not currently being processed) (S613). When the life time expiration of the specific data is imminent (S614), the user is requested to input a life time extension password. If the user enters the password for extending the life time (S615), the security daemon compares with the stored life time extension password and determines whether it matches (S616). In this case, instead of using a general password for security, the password for life time extension may be hashed and stored and compared with a hash value of the input password.

When the life time extension passwords match, the security daemon transmits a user time extension request by transmitting user authentication information and corresponding data identification information using an electronic signature or a time stamp to an external server (S617). The external server authenticates the user and determines whether the life time extension is approved by checking the level of the corresponding data and checking the life time (S618).

If the life time extension is approved, the external server transmits new life time information to the device, and the device updates and stores the life time information of the corresponding data with new life time information (S620). When it is impossible to extend the life time, the external server transmits an "additional response request" to the device, and the device performs an additional operation such as turning off the device according to the additional response request (S619).

Lifetime in the third security algorithm may be flexibly determined by a user or an administrator in consideration of security needs and ease of use.

In the above, it is assumed that the data is stored in the apparatus, but the data is stored in an external data synchronization server, and may be decoded and transmitted to the apparatus only when the apparatus is actually used.

The "external server" or "data synchronization server" for performing the second and third security algorithms refers to a device that is linked to the device through an internet network, a wired / wireless communication network, and the like. And as long as it has the following functions:

In other words, the external server must have a database that stores linked device or user-specific information, data to be synchronized, and metafiles for the data, and user authentication and life time extension using authentication information received from the device. There should be controls for judging approval. Since the configuration of the data synchronization server is disclosed in Korean Patent Application No. 2000-39327 of the applicant, detailed description thereof will be omitted here.

The present invention is not limited to the three levels of security classification described above and the application of the first to third security algorithms, and all of which classify important data of the computing device into security levels and apply a security algorithm suitable for each level. It should be understood as a concept involving the method.

According to the present invention, security can be further improved by encrypting, storing, and managing all stored data, and decrypting and displaying the data temporarily when it is output.

In addition, by dividing the data of the computing device into multiple classes according to importance or security needs, and applying a specific security algorithm suitable for each class, data security and ease of use can be simultaneously achieved.

In addition, by storing the encryption / decryption key of the data on an external server instead of the device, even if the device is illegally acquired and cracked, access to the data can be prevented, and specific data is monitored by giving a lifetime. This can improve security.

Claims (10)

A data security method for each layer of a computing device having a security management program module, After user authentication and / or device access to the device, the security management program module checks the security level of the requested data when there is a request for access to specific data from the application program of the device Performing a predetermined security algorithm according to the checked security level to perform an access authentication on the corresponding data; And a data processing step of allowing access to the corresponding data only when the access is authenticated as a result of performing the security algorithm. The method of claim 1, Security algorithm execution step and data processing step for a specific level of data, A first step of extracting or calculating an encryption / decryption key stored in the device without individual authentication for each data within a particular class; And a second step of decrypting the corresponding data by using the extracted / calculated encryption / decryption key and transmitting the decrypted data to the application program. The method of claim 2, Security algorithm execution step and data processing step for a specific level of data, A first step of receiving device or user authentication from an external server or device interworking with the computing device; A second step of receiving an encryption / decryption key for decrypting data from an external server or device, and And a third step of decrypting the corresponding data using the received encryption / decryption key and transmitting the decrypted data to the application program. The method according to any one of claims 1 to 3, Security algorithm execution step and data processing step for a specific level of data, A first step of authenticating a user or a device from an external server or device interworking with the computing device, A second step of receiving an encryption / decryption key for decrypting data from an external server or device, A third step of decrypting the corresponding data using the received encryption / decryption key and delivering the data to the application program; A fourth step of monitoring whether the life time assigned to the data requested for access has expired, and if the life time is about to expire, forcing the user to enter a password for extending the life time; A fifth step of transmitting a life time extension request to the external server or device when the life time extension password matches; And a sixth step of extending and updating the life time of the data and allowing access to the data continuously only when the life time extension request is authenticated by the external server or device. Rating data security methods. The method of claim 4, wherein The security management program monitors the lifetime of data that is not currently being processed among the data stored in the device, and when the expiration of the lifetime is imminent, the user inputs a password for extending the lifetime. In addition, the life time extension request is transmitted to the external server if the life time extension password is matched, and the life time extension of the corresponding data is only provided if the life time extension is approved. A data security method for each class of computing device. The method of claim 4, wherein After the data processing step, the user authentication is performed at predetermined intervals, and the data processing step is continued only when the user re-authentication is performed. If the user re-authentication fails, the data processing is terminated and the processed data is encrypted. And storing the user re-authentication step. The method of claim 4, wherein After the data processing step, if the processing of the data is terminated or the power of the device is turned off, further comprising the step of encrypting and storing the data at the time point of the data security method of the computing device, characterized in that . The method of claim 4, wherein When the device is first turned off and then turned on again, the first access to the data is performed by using the previous encryption / decryption key stored before it is turned off, and when storing the data again, a new encryption / decryption key is generated and used. Rating data security methods. The method of claim 8, The new encryption / decryption key Extracted based on one or more of random information generated by a pseudo random number generator, specific information including current time information, and key stroke, mouse movement, and touch screen input information. A method of classifying data security of a computing device, characterized by being generated by hashing or encrypting existing seed information which is a random number. The method of claim 1, The checking of the security level is performed by referring to meta data stored in a computer device or an external server.